Biology ETDs

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Homozygous lethal and nonlethal second chromosomes were isolated by the Cy-technique from a laboratory population of Drosophila melanogaster and placed opposite dp chromosomes to study the viability, fecundity, and longevity of heterozygotes. Viability was determined by testing 12 lethal and six non lethal chromosomes. Males heterozygous for the Cy and the test chromosomes were mated with dp/dp females. From the progeny, dp/+ males were crossed to dp/dp females. From the progeny, dp/+ males were crossed to dp/dp females. The relative proportion of dp/+ flies in the progeny would be expected to be the same in lethal and nonlethal classes if the lethal chromosomes were normal in the heterozygotes. The viabilities of lethal and nonlethal heterozygotes did not differ significantly. To determine female fecundity and longevity, I studied 12 lethal and five nonlethal chromosomes by testing dp/+ females from the cross Cy/+ X dp/dp individually for fecundity and longevity. There was no significant difference in either fecundity or longevity of lethal and nonlethal heterozygotes.

Although the lethal chromosomes did not influence strongly viability, fecundity, or longevity, they were susceptible to microenvironmental fluctuations in all the tests, as revealed by the higher variance among replicate cultures than among individual chromosomes. This was true for nonlethals only in viability. It was inferred that the developmental homeostasis of both lethal and non­lethal heterozygotes was disturbed, and that the physiological homeostasis of the lethals was impaired.



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Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

William Wayne Johnson

Second Committee Member

Martin William Fleck

Third Committee Member

Clarence Clayton Hoff

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